1. Field of the Invention
Embodiments described herein relate generally to a coupling which connects tubes such as hoses or pies to each other or the tube to another device such as a pump.
2. Description of the Related Art
Conventionally, safety valves have been used for protecting devices, couplings, hoses and the like from breakage caused by an abnormal pressure surge of a transfer fluid on steam and gas supply lines. However, a conventional safety valve has not been assumed to be used in combination with a large number of hoses, shutoff nozzles, and the like or to be used for a large-capacity foam-water discharge system using a foam fire-extinguishing solution used for such an occasion that an oil storage tank at a petroleum complex catches fire.
In a major petroleum complex, dozens of large-size oil storage tanks are installed. For example, such an oil storage tank has a diameter of 83 meters, a height of 24 meters, and a capacity of 120 thousand kiloliters. If a large-size oil storage tank catches fire, it is impossible to handle the situation with conventional firefighting equipment including fire pumps and fire hoses. The conventional firefighting equipment can discharge water at a maximum of about 2,000 [L/min] and thus cannot possibly handle a fire set to a large-size oil stage tank. Further, it has been said that a large-capacity foam-water discharge system which can discharge water at a rate of 10,000 to 30,000 [L/min] is required for a fire at a large-scale petroleum complex.
When a fire breaks out at a large-scale petroleum complex, a large-capacity foam-water discharge means is obviously required, but if a water source is located at a long distance of a several kilometers away from an oil storage tank, a means of supplying a large volume of water over such a long distance using a water supply hose is also required. When a large volume of water is transported over a long distance, as might be expected, a water supply hose will have a significantly large loss of pressure.
Therefore, to minimize the pressure loss during the transport operation, a large-diameter water supply hose and a large-diameter coupling (type 300 and type 200) are required. Further, it is necessary to pressurize a water supply hose, maintain predetermined pressure, and reliably supply water to a water cannon installed at the end of the water supply hose by installing a water supply pump and a pressure pump are installed in the middle of the water supply pathway of the water supply hose.
FIG. 19 shows an example of a large-capacity foam discharge system. In FIG. 19, reference number 11 indicates a water source such as the sea or a lake, and reference number 12 indicates the land. Reference number 13 indicates a fire site, namely, an oil storage tank at a petroleum complex located at a distance of a several kilometers away from the water source 11. A submersible pump 14 is sunk in the water source 11 and is driven by an engine generator 15 settled on the land 12. A water supply pump 16 is settled on the land 12. A discharge port 17 of the submersible pump 14 and an intake port 18 of the water supply pump 16 are connected to each other by a plurality of water supply hoses 19. To use the plurality of water supply hoses 19, the submersible pump 14 has, for example, four discharge ports 17, and the water supply pump 16 has, for example, four intake ports 18. The water supply hoses 19 which connect the discharge ports 17 and the intake ports 18, respectively, include, for example, four hoses, each having a diameter of 6 inches and a length of 10 meters, and three adjustment hoses, each having a diameter of 6 inches and a length of 3 meters. The water supply pump 16 is connected to a pressure pump 20 via a water supply pathway 21, and the pressure pump 20 is installed in a part of the land 12 which is close to the oil storage tank 13 at the fire site and is far from the water supply pump 16.
Next, the water supply pathway 21 which connects the water supply pump 16 and the pressure pump 20 will be described. The water supply pump 16 has a plurality of discharge ports, for example, four discharge ports 22, and similarly, the pressure pump 20 has a plurality of intake ports, for example, four intake ports 23. The discharge ports 22 of the water supply pump 16 are connected to one ends of four water supply hoses 24, for example, each having a diameter of 6 inches and a length of 50 meters, and the other ends of the water supply hoses 24 are connected to the intake side of a first manifold 25. The first manifold 25 has discharge ports, each having a diameter of 8 inches and connected to one ends of two water supply hoses 26, each having a length of 1000 meters. The other ends of the water supply hoses 26 are connected to a second manifold 27. The second manifold 27 has intake ports, each having a diameter of 6 inches and has discharge ports, respectively connected to one ends of four water supply hoses 28, each having a length of 10 meters. The other ends of these water supply hoses 28 are connected to the intake ports 23 of the pressure pump 20.
Further, in FIG. 19, reference number 29 indicates an undiluted solution transport vehicle loaded with a tank 30 containing foam-fire-extinguishing chemical agent (undiluted solution) to be used for extinguishing a fire set to the oil storage tank 13. The tank 30 of the undiluted solution transport vehicle 29 is connected to one ends of two rubber intake pipes 31, each having a diameter of 3 inches and a length of 10 meters, and the other ends of the rubber intake pipes 31 are connected to intake ports 33 of an undiluted solution pump 32. Discharge ports 34 of the undiluted solution pump 32 are connected to one ends of two canvas hoses 35, each having a diameter of 2.5 inches and a length of 10 meters. The other ends of the canvas hoses 35 are connected to undiluted solution intake ports 37 of the pressure pump 20 via a mixer 36, and in the mixer 36, the foam-fire-extinguishing chemical agent (undiluted solution) is diluted with water supplied from the water source 11 at a dilution rate of, for example, 1%, and a foam-fire-extinguishing solution is produced.
Further, the pressure pump 20 has a plurality of discharge ports, for example, four discharge ports 38. Similarly, a manifold 40 of a foam-water cannon 39 has a plurality of connection joints, for example, four connection joints (couplings) 41. The discharge ports 38 of the pressure pump 20 and the connection joints (couplings) 41 of the intake side of the manifold 40 of the foam-water cannon 39 are connected to each other, for example, by four water supply hoses 42, each having a length of 20 meters. Further, the foam-water cannon 39 discharges a large volume of foam to the fire site (oil storage tank) 13 to extinguish the fire.
Each of the water supply hoses 24, 28, 42 or the like comprises connection joints (couplings) 43 at both ends and is detachably connected to pumps or the like via the connection joints (couplings) 43. According to the fire extinguishing situation, it is possible to increase or decrease the number of the water supply hoses 24, 28 and 42. In the discharge ports 22 of the water supply pump 16 and the discharge ports 38 of the pressure pump 20, the connection joints (couplings) 43 are provided via valves 44.
In the meantime, during the firefighting operation using the above-described large-capacity foam-water discharge system, the operation of the system is monitored. In the operation, there is a possible of accidents, that is, water leakage may occur from between the connection joint 43 and the water supply hose 24 or 42 for some reason or other, or water leakage may occur when the connection joint 43 is broken. For example, if water leakage occurs in one of the four connection joints 43 connected to the connection joints 41 of the nearest manifold 40 to the foam cannon 39, an operator of the foam-water cannon 39 reports the situation to a supervisor, and the supervisor contacts an operator who is monitoring the pressure pump 20 by radio or the like and instructs the operator to decrease the rotation speed of the pump and then stop the operation of the pump, and also instruct the operator to stop the water supply pump 16 and the submersible pump 14 and then close the four valves 44 connected to the four hoses including the water supply hose 42 where the water leakage has occurred.
Then, the operator immediately instructs an operator who is monitoring the water supply pump 16 to decrease the rotation speed of the pump and then stop the operation of the pump, and instructs an operator who is monitoring the submersible pump 14 to decrease the rotation speed of the pump and then stop the operation of the pump after the supply pump 16 has stopped. In this case, there will be no trouble if the operator who is monitoring the pressure pump 20 closes the four valves 44 connected to the four hoses including the water supply hose 42 where the water leakage has occurred after the operations of the water supply pump 16 and the submersible pump 14 are completely stopped. However, if the operator makes haste to close the four valves 44 while the water supply pump 16 and the submersible pump 14 are still rotating, a fluid pressure surge, namely, a water hammer is created by dynamic pressure which is different from rated pressure (static pressure) of the water supply pump 16 and the like and is applied to the water supply hoses 28, 26, 24, and the like. Therefore, it may burst the water supply hoses 28, 26, 24, and the like or break the couplings 43 attached to these hoses.
Further, based on the assumption that the operators perform inappropriate operations and the water supply hoses 24, 26, 28, 42 and the like may be subjected to such high pressure, the pressure resistance level of the water supply hoses 24, 26, 28, 42 and the like is designed to some extent. However, such water supply hoses 24, 26, 28 and 42 having high pressure resistance level will be expensive and will be difficult to maneuver as the water supply hoses themselves become heavier and harder.
Still further, in a large-capacity foam-discharge system of this kind, a water supply line is composed of a several tens of hoses. Then, a safety valve is attached to a nearest manifold to a high-pressure fluid pump or the like. However, if a valve of a discharge port, an intake port, or the like is abruptly closed, a water hammer is created, and the pressures of the valve on the water source side increases up to about 2 to 3 times of the normal pressure of the water transport operation. Further, in a case where the water supply line equips with a plurality of pumps for preventing a pressure loss on the middle of the water supply line, a water hammer tends to be created on the water supply line by lack of cooperation between these pumps. In addition, a large number of valves are provided in various locations on the water supply line. Therefore, a water hammer may be created everywhere on the water supply line.
Therefore, to prevent breakage of water-discharge equipment, a coupling, a hose and the like or to avoid fatal accidents by such an abnormal pressure surge on a water supply line, a coupling with a safety mechanism has been proposed (JP 4834423 B). The coupling with the safety mechanism (connection joint) 50 is shown in FIG. 20. In this structure, a safety valve (pressure valve) is attached to the body of coupling 50. A branch pipe 52 is provided in the middle of a cylindrical coupling body 51 of the coupling 50, and a safety valve 80, which will be described later, is attached to the branch pipe 52. Therefore, the branch pipe 52 and the safety valve 80 are arranged perpendicularly with respect to the axis of the coupling body 51, and the coupling 50 has a T shape as a whole.
Further, as shown in FIG. 20, coupling portions 57a and 57b, which have the same structure as each other, are assembled into the ends of the coupling body 51, respectively. Each of the coupling portions 57a and 57b comprises a cylinder body 58. The cylinder body 58 has a cylindrical shape, and at the outer edge of the cylinder body 58, a sealing member 59 such as a rubber packing is attached. Further, the coupling portions 57a and 57b are axially coupled with those of the other coupling 50, which have the same structure as the one coupling 50, and at this time, the sealing members 59 at the outer edges of the cylinder bodies 58 are attached to those of the other couplings 50, and fluid passages 78 in the cylinder bodies 58 are, as maintained to be sealed from the outside, communicated with those of the other couplings 50.
Still further, in each of the coupling portions 57a and 57b, a coupling ring 61 is attached to the cylinder body 58, and at the outer edge of the coupling ring 61, a plurality of engagement projections, for example, nine engagement projections 70 are provided. These engagement projections 70 are circumferentially arranged at regular intervals and axially project outward with respect to the sealing member 59. The regions between the engagement projections 70 are engagement recesses 71. Further, when the coupling portions 57a and 57b are axially coupled with those of the other couplings 50, the engagement projections 70 of the coupling portion 57a of the one coupling 50 are fitted into the engagement recesses 71 of the coupling portion 57b of the other coupling 50, and the engagement projections 70 of the coupling portion 57b of the other coupling 50 are fitted in the engagement recesses 71 of the coupling portion 57a of the one coupling 50. That is, the coupling is a unisex coupling and is complementarily engaged with the other coupling.
Still further, a step-like hook, namely, an engagement hook 72 is formed in one side surface 70a of each engagement projection 70, and the engagement hooks 72 of the one engagement projections 70 are circumferentially engaged with the engagement hooks 72 of the engagement projections 70 of the other coupling 50.
Still further, a biasing mechanism 73 is provided in the other side surface of the engagement projection 70, which is opposite to the side surface of the engagement projection 70 provided with the engagement hook 72. The biasing mechanism 73 comprises a steel ball 74 and a spring (not shown) which pushes the steel ball 74 in the projecting direction. Therefore, when the engagement projections 70 are engaged with the engagement recesses 71, the steel balls 74 of the one engagement projections 70 are pressed against the steel balls 74 of the other engagement projections 70, and the other side surfaces of the engagement projections 70, that is, the side surfaces of the engagement projections 70 provided with the steel balls 74 are separated from each other. As a result, the side surfaces of the engagement projections 70, that is, the side surfaces provided with the engagement hooks 72 are brought closer to each other, and thus the engagement hooks 72 are engaged with each other.
Still further, the safety valve (pressure valve) 80 is provided at the end of the branch pipe 52 as a safety valve mechanism which discharges an internal fluid to the outside when the inner pressure of the branch pipe 52 exceeds a set pressure level. A valve body 81 of the safety valve 80 is detachably attached to the end of the branch pipe 52. In the valve body 81, an inward-projecting valve seat element 84 and a valve body 86 are provided. When the pressure of the fluid passage 78 in the coupling 50 is abnormally high, the valve body 86 opens such that the fluid passage 78 becomes open to the outside.
An upward-projecting valve rod 87 is provided in the valve element 86. The valve rod 87 penetrates through a through-hole 90 of an adjustment screw member 89 screwed into a female screw portion 88 formed at the top of the valve body 81. The valve rod 87 is supported in an axially movable manner with respect to the adjustment screw member 89. A coil spring 91 is wound around the valve rod 87 and is interposed between the lower surface of the adjustment screw member 89 and the upper surface of the valve element 86 in a compressed manner. It is possible to adjust the pressing force of the coil spring 91 by rotating the adjustment screw member 89 and determining the vertical movement position of the adjustment screw member 89. In this way, it is possible to adjust a setting pressure at which the valve element 86 opens. A relief hole 92 which leads to the outside is provided in the circumferential wall of the valve body 81, and the fluid passage 78 is communicated with the outside through the relief hole 92.
Further, when the pressure of the foam fire-extinguishing solution or the like in the fluid passage 78 exceeds the setting pressure, the valve body 86 is pushed up against the pressing force of the coil spring 91, and as the valve body 86 is separated from the valve seat 84, a part of the foam fire-extinguishing solution or the like in a fluid passage 85 is discharged to the outside through the relief hole 92, and the pressure of the solution in the fluid passage 78 is reduced. Therefore, it is possible to prevent such a situation where fluid pressure higher than the setting pressure is applied to other fire hoses, couplings, and the like.